The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers
The dense mixture of iceberg of various sizes and sea ice observed in many of Greenland's fjords, called ice mélange ( sikussak in Greenlandic), has been shown to have a significant impact on the dynamics of several Greenland tidewater glaciers, mainly through the seasonal support it provides t...
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ftcopernicus:oai:publications.copernicus.org:tc105906 2023-05-15T16:21:09+02:00 The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers Wehrlé, Adrien Lüthi, Martin P. Vieli, Andreas 2023-01-23 application/pdf https://doi.org/10.5194/tc-17-309-2023 https://tc.copernicus.org/articles/17/309/2023/ eng eng doi:10.5194/tc-17-309-2023 https://tc.copernicus.org/articles/17/309/2023/ eISSN: 1994-0424 Text 2023 ftcopernicus https://doi.org/10.5194/tc-17-309-2023 2023-01-30T17:22:43Z The dense mixture of iceberg of various sizes and sea ice observed in many of Greenland's fjords, called ice mélange ( sikussak in Greenlandic), has been shown to have a significant impact on the dynamics of several Greenland tidewater glaciers, mainly through the seasonal support it provides to the glacier terminus in winter. However, a clear understanding of shorter-term ice mélange dynamics is still lacking, mainly due to the high complexity and variability of the processes at play at the ice–ocean boundary. In this study, we use a combination of Sentinel-1 radar and Sentinel-2 optical satellite imagery to investigate in detail intra-seasonal ice mélange dynamics and its link to calving activity at three major outlet glaciers: Kangerdlugssuaq Glacier, Helheim Glacier and Sermeq Kujalleq in Kangia (Jakobshavn Isbræ). In those fjords, we identified recurrent ice mélange weakening (IMW) episodes consisting of the up-fjord propagation of a discontinuity between jam-packed and weaker ice mélange towards the glacier terminus. At a late stage, i.e., when the IMW front approaches the glacier terminus, these episodes were often correlated with the occurrence of large-scale calving events. The IMW process is particularly visible at the front of Kangerdlugssuaq Glacier and presents a cyclic behavior, such that we further analyzed IMW dynamics during the June–November period from 2018 to 2021 at this location. Throughout this period, we detected 30 IMW episodes with a recurrence time of 24 d, propagating over a median distance of 5.9 km and for 17 d, resulting in a median propagation speed of 400 m d −1 . We found that 87 % of the IMW episodes occurred prior to a calving event visible in spaceborne observations and that ∼75 % of all detected calving events were preceded by an IMW episode. These results therefore present the IMW process as a clear control on the calving activity of Kangerdlugssuaq Glacier. Finally, using a simple numerical model for ice mélange motion, we showed that a slightly biased random motion of ice ... Text glacier Greenland greenlandic Jakobshavn Jakobshavn isbræ Kangia Kujalleq Sea ice Sermeq Kujalleq Tidewater Copernicus Publications: E-Journals Greenland Jakobshavn Isbræ ENVELOPE(-49.917,-49.917,69.167,69.167) Kujalleq ENVELOPE(-46.037,-46.037,60.719,60.719) The Cryosphere 17 1 309 326 |
institution |
Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The dense mixture of iceberg of various sizes and sea ice observed in many of Greenland's fjords, called ice mélange ( sikussak in Greenlandic), has been shown to have a significant impact on the dynamics of several Greenland tidewater glaciers, mainly through the seasonal support it provides to the glacier terminus in winter. However, a clear understanding of shorter-term ice mélange dynamics is still lacking, mainly due to the high complexity and variability of the processes at play at the ice–ocean boundary. In this study, we use a combination of Sentinel-1 radar and Sentinel-2 optical satellite imagery to investigate in detail intra-seasonal ice mélange dynamics and its link to calving activity at three major outlet glaciers: Kangerdlugssuaq Glacier, Helheim Glacier and Sermeq Kujalleq in Kangia (Jakobshavn Isbræ). In those fjords, we identified recurrent ice mélange weakening (IMW) episodes consisting of the up-fjord propagation of a discontinuity between jam-packed and weaker ice mélange towards the glacier terminus. At a late stage, i.e., when the IMW front approaches the glacier terminus, these episodes were often correlated with the occurrence of large-scale calving events. The IMW process is particularly visible at the front of Kangerdlugssuaq Glacier and presents a cyclic behavior, such that we further analyzed IMW dynamics during the June–November period from 2018 to 2021 at this location. Throughout this period, we detected 30 IMW episodes with a recurrence time of 24 d, propagating over a median distance of 5.9 km and for 17 d, resulting in a median propagation speed of 400 m d −1 . We found that 87 % of the IMW episodes occurred prior to a calving event visible in spaceborne observations and that ∼75 % of all detected calving events were preceded by an IMW episode. These results therefore present the IMW process as a clear control on the calving activity of Kangerdlugssuaq Glacier. Finally, using a simple numerical model for ice mélange motion, we showed that a slightly biased random motion of ice ... |
format |
Text |
author |
Wehrlé, Adrien Lüthi, Martin P. Vieli, Andreas |
spellingShingle |
Wehrlé, Adrien Lüthi, Martin P. Vieli, Andreas The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers |
author_facet |
Wehrlé, Adrien Lüthi, Martin P. Vieli, Andreas |
author_sort |
Wehrlé, Adrien |
title |
The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers |
title_short |
The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers |
title_full |
The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers |
title_fullStr |
The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers |
title_full_unstemmed |
The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers |
title_sort |
control of short-term ice mélange weakening episodes on calving activity at major greenland outlet glaciers |
publishDate |
2023 |
url |
https://doi.org/10.5194/tc-17-309-2023 https://tc.copernicus.org/articles/17/309/2023/ |
long_lat |
ENVELOPE(-49.917,-49.917,69.167,69.167) ENVELOPE(-46.037,-46.037,60.719,60.719) |
geographic |
Greenland Jakobshavn Isbræ Kujalleq |
geographic_facet |
Greenland Jakobshavn Isbræ Kujalleq |
genre |
glacier Greenland greenlandic Jakobshavn Jakobshavn isbræ Kangia Kujalleq Sea ice Sermeq Kujalleq Tidewater |
genre_facet |
glacier Greenland greenlandic Jakobshavn Jakobshavn isbræ Kangia Kujalleq Sea ice Sermeq Kujalleq Tidewater |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-17-309-2023 https://tc.copernicus.org/articles/17/309/2023/ |
op_doi |
https://doi.org/10.5194/tc-17-309-2023 |
container_title |
The Cryosphere |
container_volume |
17 |
container_issue |
1 |
container_start_page |
309 |
op_container_end_page |
326 |
_version_ |
1766009172262912000 |